1. Field of the Invention
This invention relates to generally to the chemical mechanical polishing of the product material and, more particularly, to the chemical mechanical polishing of device material during the fabrication of semiconductor devices. In order to provide uniform polishing, the polishing material or slurry must be uniformly distributed over the polishing pad and over the product material being processed.
2. Description of the Related Art
Referring to FIG. 1A and FIG. 1B, a top view and side view, respectively, of the arrangement of the polishing apparatus according to the prior art is shown. A polishing pad 10 rotates with an angular velocity .omega..sub.p is shown. A tube 15 having an outlet port at or near the center of rotation of the polishing pad 10. A polishing material or slurry 19 is transmitted through the tube and deposited on the polishing pad at or near the center of rotation of the polishing pad. The polishing material is distributed over the surface of the polishing pad 10. Product carriers 11, rotating with an angular velocity .omega..sub.c have a piece of the product material 16 attached to an first end. The rotating carrier 11 is lowered until the product material 16 comes in contact with the polishing material 19. The mechanical and/or chemical properties of polishing material 19, as it contacts the product material results in a polished surface on the product material 16.
The uniform polishing of the product material(s) 16 requires a uniform distribution of the polishing material 19. In the past, concentric grooves or channels 101 have been fabricated in the pad 10 to make the distribution of polishing material more uniform. While this geometry of the channels provided an improvement in the polishing process, more stringent requirements for product material surfaces have resulted in this channel geometry no longer providing a satisfactory polished surface.
A need has therefore been felt for a technique for improving the distribution of the polishing material over the pad and over the product material during the polishing process.